The problem of residual cross-contamination between patients is of serious concern to the public and dental profession. This problem has received considerable attention due to the publicity of many known illnesses and diseases which may be communicated by the transfer of infected body fluids between patients. A dental syringe is often used to apply a suction or fluid, such as water or air, to the inside of a patient's mouth. Where a fluid is dispensed, the syringe is connected to a pressurized delivery system. In some dental syringe systems, an optional draw-back apparatus may be used with the delivery system. When the application of a liquid ceases, the draw-back apparatus produces a partial vacuum within the delivery lines, syringe and beak. The partial vacuum draws the liquid located within the syringe back into the delivery system, removing the liquid from the beak of the syringe. The draw-back apparatus prevents the leaking or dripping of liquid from the discharge orifice of the beak when the syringe is not used. Unfortunately, when the syringe is released from dispensing the liquid, the draw-back apparatus may suck contaminants, such as germs, blood, or saliva, from within the patient's mouth into the syringe or delivery system. These contaminants remain within the syringe or delivery system until liquid is subsequently dispensed, possibly into another patient's mouth.
Devices using sanitary covers have been designed in an effort to reduce the occurrence of injuries caused by dental hardware.
Curry (U.S. Pat. No. 1,485,963) discloses a disposable cover for a dental handpiece. The cover protects the handpiece from contacting the hand of the user or the mouth of the patient.
Fehrman (U.S. Pat. No. 2,655,725) discloses a grinding implement for use with small animals, particularly chinchillas, having a readily adjustable guard for the rotary burr to protect the mouth of the animal against injury.
Ikse (U.S. Pat. No. 2,696,669) discloses a device for supplying liquid during dental operations. Ikse ('669) teaches that the nozzle may be interchangeable.
Hawk (U.S. Pat. No. 4,286,950) discloses a removable cover for a dental handpiece, to protect the tool and enclose it when not in use.
These disclosures are believed to illustrate the general scope of the prior art in this area of dental technology. The applicant submits that these disclosures taken alone or together do not teach the concepts embodied in this invention.